A person who spreads religious teachings, especially in Christianity. Can also be used metaphorically for a passionate advocate of an idea.
He is known as a zealous evangelist.
その伝道師は村々を回って説教した。
The missionary traveled from village to village preaching.
Compound of 伝道 (preaching, evangelism) and 師 (master, teacher). The term was coined in the Meiji era to translate the Christian concept of evangelist.